ANATOMY OF MEGAPTERA LONGIMANA. 



103 



what triangular, is directed straight up ; the 5th, now square- 

 shaped, a little forwards ; the 6th, straight up ; the 7th, a little 

 backwards. The remaining spines all slope backwards, increas- 

 ingly so to the 14th dorsal. After the 1st lumbar the slope 

 diminishes a very little to the 6th, then a little more to the 

 9th, and still more from the 10th lumbar to the 8rd caudal. 

 Behind the latter the slope begins to increase, but the processes 

 are too irregularly formed to give precise indication. 



A convenient way of measuring the amount of the slope is to 

 take a perpendicular from the plane of the back of the body. 

 But the result by this method is influenced by the length of the 

 spine, and in Megaptera (as compared with B. musculus) by 

 the length and backward obliquity of the laminae in the dorsal 

 and anterior lumbar regions, thus carrying the base of the 

 spines backwards in these regions as compared with the middle 

 and posterior lumbar regions. The result by the perpendicular 

 line, therefore, does not always correspond to the real obliquity, 

 as ascertained by taking the angle. 



The figures in the first column of the subjoined table (Table 

 IV.) give the distance of the hack of the body behind the 

 middle of the top of the spine ; the second column gives the 

 true obliquity, the angle formed by the axis of the body and 

 the axis of the spinous process. For comparison, the same 

 measurements in B. musculus are given. 



Table IV. 



giving the Amount of Ohliquity of the Sjnnous Processes jn 

 Megaptera and B. musculus. 



Besides the points above referred to, the following may be 

 noted of the form of the spinous processes. Anterior border, 



